Mathematical model of transforming image elements to structured data based on BP neural network

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Comprehensive comparison of three diagnostic methods

Feature amount	Training time/s-1	Forecast accuracy rate/%	Overview
Colour histogram	590.160333	87.58	Short training time, average prediction accuracy
Colour moment	10.764295	87.82	Longest training time, average prediction accuracy
Centreline colour matrix	46.679	750, 93.37	Short training time and high prediction accuracy

Comparison of the accuracy of the number of neurons in different hidden layers

Number of input neurons	Colour moment accuracy rate/%	Colour histogram accuracy rate/%	Centreline colour matrix accuracy rate/%
5	86.87	83.88	93.37
10	87.82	87.58	93.37
15	87.70	85.37	93.13
20	87.76	82.69	93.13
30	87.88	85.67	92.84

Diagnosis results based on the feature amount of the colour histogram

Serial number	1	2	3	4	5	Average
Accuracy/%	86.27	87.16	88.06	88.66	87.76	87.58

Diagnosis results based on the colour moment feature quantity

Serial number	1	2	3	4	5	Average
Accuracy/%	88.06	86.87	89.25	88.36	86.57	87.82

Table 4 Diagnosis results based on the colour matrix of the centreline of the insulator

Serial number	1	2	3	4	5	Average
Accuracy/%	93.43	93.73	92.84	93.43	93.43	93.37